Instruments and methods for forming a cavity

ABSTRACT

A cavity creating device having a cavity creating axis is introduced through a percutaneous access path into a cancellous bone volume, e.g., within a vertebral body. The cavity creating device is manipulated to form a cavity in the cancellous bone volume. The manipulation includes deflecting the cavity creating device along the cavity creating axis relative to the axis of the access path. A material, such as bone cement, can be conveyed into the cavity.

RELATED APPLICATIONS

This application is divisional of co-pending U.S. patent applicationSer. No. 10/436,551, filed May 13, 2003, which is a divisional of U.S.patent application Ser. No. 09/918,942, filed Jul. 31, 2001 (now U.S.Pat. No. 6,623,505), which is a divisional of U.S. patent applicationSer. No. 09/404,662, filed Sep. 23, 1999, now U.S. Pat. No. 6,280,456,which is a divisional of U.S. patent application Ser. No. 08/911,827,filed Aug. 15, 1997, now U.S. Pat. No. 5,972,015, each of which isincorporated herein by reference.

FIELD OP THE INVENTION

The invention, relates to expandable structures, which, in use, aredeployed in interior body regions of humans and other animals.

BACKGROUND OF THE INVENTION

The deployment of expandable structures into interior body regions iswell known. For example, expandable structures, generically called“balloons,” are deployed during angioplasty to open occluded bloodvessels. As another example, U.S. Pat. Nos. 4,969,888 and 5,108,404disclose apparatus and methods the use of expandable structures for thefixation of fractures or other osteoporotic and non-osteoporoticconditions of human and animal bones.

Many interior regions of the body, such as the vasculature and interiorbone, possess complex, asymmetric geometries. Even if an interior bodyregion is somewhat more symmetric, it may still be difficult to gainaccess along the natural axis of symmetry.

For example, deployment of an expandable structure in the region ofbranched arteries or veins can place the axis of an expandable structureoff-alignment with the axis of the blood vessel which the structure isintended to occupy. As another example, insertion of an expandablestructure into bone can require forming an access portal that is notaligned with the natural symmetry of the bone. In these instances,expansion of the structure is not symmetric with respect to the naturalaxis of the region targeted for treatment. As a result, expansion of thebody is not symmetric with respect to the natural axis of the targetedregion.

It can also be important to maximize the size and surface area of anexpandable structure when deployed in an interior body region. Currentmedical balloons manufactured by molding techniques are designed to beguided into a narrow channel, such as a blood vessel or the fallopiantube, where they are then inflated. In this environment, the diameter ofthe balloon is critical to its success, but the length is less so. Suchballoons only need to be long enough to cross the area of intended use,with few constraints past the effective portion of the inflated balloon.This allows conventional balloons to be constructed in three moldedpieces, comprising a cylindrical middle section and two conical ends,bonded to a catheter shaft. As a practical matter, neither the length ofthe conical end, nor the length of the bond of the balloon to thecatheter shaft, affect the function of conventional balloons, and theseregions on conventional balloons are often 1 cm in length or more.Indeed, the larger the balloon diameter, the longer the end cone, whichcreates a tradeoff between maximum effective length and maximumeffective diameter. This tradeoff makes optimization of conventionalstructures problematic in interior structures with defined lengths, suchas bone.

SUMMARY OF THE INVENTION

One aspect of the invention provides a device comprising a shaft havingan elongated shaft axis and a proximal end portion and a distal endportion. The elongated shaft is sized and configured for passage througha percutaneous access path into a cancellous bone region. The devicealso includes a cavity forming structure carried on the distal end ofthe shaft. The cavity forming device is sized and configured to bemanipulated to form a cavity in the cancellous bone region. The cavityforming structure has an elongated cavity forming axis. The devicefurther includes a mechanism for deflecting the cavity forming structurealong the elongated cavity forming axis, to shift the elongated cavityforming axis relative to the elongated shaft axis.

Another aspect of the invention provides a method that provides apercutaneous access path having an axis into bone having an interiorvolume occupied, at least in part, by cancellous bone. The methodintroduces a cavity creating device having a cavity creating axisthrough the access path into the cancellous bone volume. The methodmanipulates the cavity creating device to form a cavity in thecancellous bone volume. The manipulation includes deflecting the cavitycreating device along the cavity creating axis relative to the axis ofthe access path.

In one embodiment, a material, e.g., bone cement, is introduced into thecavity.

In one embodiment, the cavity creating device is also expanded to formthe cavity.

In one embodiment, bone comprises a vertebral body.

Features and advantages of the inventions are set forth in the followingDescription and Drawings, as well as in the appended Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral view, partially broken away and in section, of alumbar vertebra taken generally along line 1-1 in FIG. 2;

FIG. 2 is a coronal view of the lumbar vertebra, partially cut away andin section, shown in FIG. 1;

FIG. 3 is a top view of a probe including a catheter tube carrying atubular expandable structure of conventional construction, shown in asubstantially collapsed condition;

FIG. 4 is an enlarged side view of the tubular expandable structurecarried by the probe shown in FIG. 3, shown in a substantially expandedcondition;

FIG. 5 is a lateral view of the lumbar vertebra shown in FIGS. 1 and 2,partially cut away and in section, with the expandable structure shownin FIGS. 3 and 4 deployed by transpedicular access when in asubstantially collapsed condition;

FIG. 6 is a coronal view of the transpedicular access shown in FIG. 5,partially cut away and in section;

FIG. 7 is a lateral view of the transpedicular access shown in FIG. 5,with the expandable structure shown in FIGS. 3 and 4 in a substantiallyexpanded condition, forming a cavity that is not centered with, respectto the middle region of the vertebral body;

FIG. 8 is a coronal view of the transpedicular access shown in FIG. 7,partially cut away and in section;

FIG. 9 is a coronal view of the lumbar vertebra shown in FIGS. 1 and 2,partially cut away and in section, with the expandable structure shownin FIGS. 3 and 4 deployed by postero-lateral access when in asubstantially collapsed condition;

FIG. 10 is a coronal view of the postero-lateral access shown in FIG. 9,with the expandable structure shown in a substantially expandedcondition, forming a cavity that is not centered with respect to themiddle region of the vertebral body;

FIGS. 11A and 11B are side views of improved expandable structures, eachhaving an axis of expansion that is offset by an acute angle and notaligned with the axis of the supporting catheter tube;

FIG. 12 is a lateral view of the lumbar vertebra shown in FIGS. 1 and 2,partially cut away and in section, with the offset expandable structureshown in FIG. 11A deployed by transpedicular access and being in asubstantially expanded condition, forming a cavity that is substantiallycentered with respect to the middle region of the vertebral body;

FIG. 13 is a coronal view of the lumbar vertebra shown in FIGS. 1 and 2,partially cut away and in section, with the offset expandable structureshown in FIG. 11 deployed by postero-lateral access and being in asubstantially expanded condition, forming a cavity that is substantiallycentered with respect to the middle region of the vertebral body;

FIGS. 14A and 14B are side views of other embodiments of improvedexpandable structures, each having an axis of expansion that is offsetby a distance from the axis of the supporting catheter tube;

FIG. 15 is a side view of a conventional expandable structure shown inFIG. 4, enlarged to show further details of its geometry whensubstantially expanded;

FIG. 16 is a side view of an improved expandable structure, when in asubstantially expanded condition, which includes end regions havingcompound curvatures that reduce the end region length and therebyprovide the capability of maximum bone compaction substantially alongthe entire length of the structure;

FIG. 17 is a side view of an improved expandable structure, when in asubstantially expanded condition, which includes end regions havingcompound curvatures that invert the end regions about the terminalregions, where the structure is bonded to the supporting catheter tube,to provide the capability of maximum bone compaction substantially alongthe entire length of the structure;

FIG. 18 is a side section view of an improved expandable structure, whenin a substantially expanded condition, which includes end regions thathave been tucked or folded about the terminal regions, where thestructure is bonded to the supporting catheter tube, to provide thecapability of maximum bone compaction substantially along the entirelength of the structure;

FIG. 19 is a side section view of a tubular expandable structure havinga distal end bonded to an inner catheter tube and a proximal end bondedto an outer catheter tube, the inner catheter tube being slidable withinthe outer catheter tube;

FIG. 20 is a side section view of the tubular expandable structure shownin FIG. 19, after sliding the inner catheter tube within the outercatheter tube to invert the end regions of the structure about thedistal and proximal bonds, to thereby provide the capability of maximumbone compaction substantially along the entire length of the structure;

FIG. 21 is a side section view of a tubular, expandable structure havinga distal end bonded to an inner catheter tube and a proximal end bondedto an outer catheter tube, the inner catheter tube and structure beingmade of a more compliant material than the outer catheter tube toprovide proportional length and diameter expansion characteristics;

FIG. 22 is an enlarged plan view of a branched blood vasculature region,in which an occlusion exists;

FIG. 23 is a further enlarged view of the branched blood vasculatureregion shown in FIG. 22, in which an asymmetric expandable structure ofthe type shown in FIG. 11 is deployed to open the occlusion;

FIG. 24 is a plan view of a sterile kit to store a single use probe,which carries an expandable structure as previously shown;

FIG. 25 is an exploded perspective view of the sterile kit shown in FIG.24;

FIG. 26 is a side view, with parts broken away and in section, of anexpandable structure having an enclosed stiffening member, to straightenthe structure during passage through a guide sheath into an interiorbody region; and

FIG. 27 is a side view of the expandable structure shown in FIG. 27,after deployment beyond the guide sheath and into the interior bodyregion, in which the stiffening member includes a distal region having apreformed bend, which deflects the structure relative to the axis of theguide sheath.

The invention may be embodied in several forms without departing fromits spirit or essential characteristics. The scope of the invention isdefined in the appended claims, rather than in the specific descriptionpreceding them. All embodiments that fall within the meaning and rangeof equivalency of the claims are therefore intended to be embraced bythe claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment first describes improved systems and methodsthat embody features of the invention in the context of treating bones.This is because the new systems and methods are advantageous when usedfor this purpose.

Another preferred embodiment describes the improved systems and methodsin the context of relieving constrictions or blockages within branchedblood vessels. This is because the vasculature also presents anenvironment well suited to receive the benefits of the invention.

The two environments are described for the purpose of illustration.However, it should be appreciated that the systems and methods asdescribed are not limited to use in the treatment of bones or thevasculature. The systems and methods embodying the invention can be usedvirtually in any interior body region that presents an asymmetricgeometry, or otherwise requires an access path that is not aligned withthe natural axis of the region.

I. Deployment in Bones

The new systems and methods will be first described in the context ofthe treatment of human vertebra. Of course, other human or animal bonetypes, e.g., long bones, can be treated in the same or equivalentfashion.

FIG. 1 shows a lateral (side) view of a human lumbar vertebra 12. FIG. 2shows a coronal (top) view of the vertebra. The vertebra 12 includes avertebral body 26, which extends on the anterior (i.e., front or chest)side of the vertebra 12. The vertebral body 26 is in the shape of anoval disk. The geometry of the vertebral body 26 is generally symmetricarranged about its natural mid-anterior-posterior axis 66, naturalmid-lateral axis 67, and natural mid-top-to-bottom axis 69. The axes 66,67, and 69 intersect in the middle region or geometric center of thebody 26, which is designated MR in the drawings.

As FIGS. 1 and 2 show, the vertebral body 26 includes an exterior formedfrom compact cortical bone 28. The cortical bone 28 encloses an interiorvolume 30 of reticulated cancellous, or spongy, bone 32 (also calledmedullary bone or trabecular bone).

The spinal canal 36 (see FIG. 2), is located on the posterior (i.e.,back) side of each vertebra 12. The spinal cord (not shown) passesthrough the spinal canal 36. The vertebral arch 40 surrounds the spinalcanal 36. Left and right pedicles 42 of the vertebral arch 40 adjoin thevertebral body 26. The spinous process 44 extends from the posterior ofthe vertebral arch 40, as do the left and right transverse processes 46.

U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose apparatus and methodsfor the fixation of fractures or other conditions of human and otheranimal bone systems, both osteoporotic and non-osteoporotic. Theapparatus and methods employ an expandable structure to compresscancellous bone and provide an interior cavity. The cavity receives afilling material, e.g., bone cement, which hardens and provides renewedinterior structural support for cortical bone. The compaction ofcancellous bone also exerts interior force upon cortical bone, making itpossible to elevate or push broken and compressed bone back to or nearits original prefracture, or other desired condition.

FIG. 3 shows a tool 48, which includes a catheter tube 50 having aproximal and a distal end, respectively 52 and 54. The catheter tube 50includes a handle 51 to facilitate gripping and maneuvering the tube 50.The handle 51 is preferably made of a foam material secured about thecatheter tube 50.

The distal end 54 carries an expandable structure 56, which FIG. 3 showsto be of conventional construction. The structure 56 is shown in FIG. 3in a substantially collapsed geometry. The structure 56 conventionallycomprises an elongated tube, formed, for example, by standard polymerextrusion and molding processes. The tubular structure 56 is bonded atits opposite ends 58 to the catheter tube 50, using, for example, anadhesive. When substantially collapsed, the structure 56 can be insertedinto an interior body region.

Tubular bodies of the type shown in FIG. 3 are made from polymermaterials and are commonly deployed in veins and arteries, e.g., inangioplasty applications. FIG. 4 shows an enlarged view of the structure56 when in a substantially expanded geometry. As FIG. 4 shows, themiddle region 64 of the tubular structure 56, when substantiallyexpanded, assumes a generally cylindrical shape, which is symmetricabout the main axis 60 of the catheter tube 50. Expansion stretches thepolymer material of the structure 56 near its bonded ends 58 to formgenerally conical end portions 62.

The structure 56 can be inserted into bone in accordance with theteachings of the above described U.S. Pat. Nos. 4,969,888 and 5,108,404.For a vertebral body 26, access into the interior volume 30 can beaccomplished, for example, by drilling an access portal 43 througheither pedicle 42. This is called a transpedicular approach, which FIG.5 shows in lateral view and FIG. 6 shows in coronal view. As FIG. 5shows, the access portal 43 for a transpedicular approach enters at thetop of the vertebral body 26, where the pedicle 42 is relatively thin,and extends at an angle downward toward the bottom of the vertebral body26 to enter the interior volume 30. As FIGS. 5 and 6 show, in a typicaltranspedicular approach, the access portal 43 aligns the catheter tubeaxis 60 obliquely with respect to all natural axes 66, 67, or 69 of thevertebral body 26.

As the conventional structure 56 expands within the interior volume 30(as FIGS. 7 and 8 show, respectively, in lateral and coronal views forthe transpedicular approach), the structure 56 symmetrically expandsabout the catheter tube axis 60, compressing cancellous bone 32 to forma cavity 68. However, since the catheter tube axis 60 is orientedobliquely relative to all natural axes 66, 67, or 69, the formed cavityis not centered with respect to the middle region MR. Instead, thecavity 68 is offset on one lateral side of the middle region MR (as FIG.8 shows) and also extends from top to bottom at oblique angle throughthe middle region MR (as FIG. 7 shows).

Due to these, asymmetries, the cavity 68 will not provide optimalsupport to the middle region MR when filled with bone cement. Since thebone cement volume is not centered about the middle region MR, thecapability of the vertebral body 26 to withstand loads is diminished.The asymmetric compaction of cancellous bone 32 in the interior volume30 may also exert unequal or nonuniform interior forces upon corticalbone 32, making it difficult to elevate or push broken and compressedbone.

As FIG. 9 shows, access to the interior volume 30 of the vertebral body26 also can be achieved by drilling an access portal 45 through a sideof the vertebral body 26, which is called a postero-lateral approach.The portal 45 for the postero-lateral approach enters at a posteriorside of the body 26 and extends at angle forwardly toward the anteriorof the body 26.

As FIG. 9 shows, the orientation of the portal 45 in a typicalpostero-lateral approach does not permit parallel or perpendicularalignment of the catheter tube axis 60 with either the mid-lateral axis67 or the mid-anterior-posterior axis 66 of the vertebral body 26. As aresult, symmetric expansion of the conventional structure 56 about thecatheter tube axis 60 forms an off-centered cavity 68′, which extendsobliquely across the middle region MR of the body 26, as FIG. 10 viewshows. As with the cavity 68 formed by the structure 56 usingtranspedicular access, the off-centered cavity 68′ formed by thestructure 56 using postero-lateral access also fails to provide optimalsupport to the middle region MR when filled with bone cement.

A. Optimal Orientation for Cancellous Bone Compaction

FIG. 11A shows an improved bone treating tool 14, which includes acatheter tube 16 carrying at its distal end 18 an expandable structure20. The catheter tube 16 can, at its proximal end, be configured likethe tube 50 shown in FIG. 3, with a handle 51 made of, e.g., a foammaterial.

FIG. 11A shows the structure 20 in a substantially expanded condition,in which the structure comprises a cylinder 21 with generally conicalportions 34, each having a top 25 and a base 27. The tops 25 of conicalportions 34 are secured about the catheter tube 16 and, in this respect,are generally aligned with the catheter tube axis 24. However, unlikethe expandable structure 56 shown in FIG. 4, the main axis 22 of thecylinder 21 and the axis 24 of the catheter tube 16 are not aligned.Instead, the cylinder axis 22 is offset at an angle A from the cathetertube axis 24. As a result, the structure 20, when substantially expanded(as FIG. 11A shows), is not symmetric with respect to the catheter tubeaxis 24.

In FIG. 11A, the bases 27 of the conical portions 34 extend generallyperpendicularly to the cylinder axis 22. In this orientation, the tops25 and the bases 27 are not parallel to each other. Other orientationsare possible. For example, in FIG. 11B, the bases 27 of the conicalportions 34 extend generally perpendicularly to the catheter tube axis24. In this orientation, the tops 2S and the bases 27 are generallyparallel to each other.

FIG. 12 shows in lateral view, the offset structure shown in FIG. 11Adeployed by a transpedicular approach in the interior volume 30 of avertebral body 26. As before shown in FIGS. 7 and 8, the transpedicularapproach in FIG. 12 does not align the catheter tube axis 24 with any ofthe natural axes 66, 67, and 69 of the body 26. However, as FIG. 12shows, the expansion of the offset cylinder 21 of the structure 20 aboutits axis 22 is not symmetric with respect to the catheter tube axis 24.Instead, expansion of the offset structure 20 is generally aligned withthe natural axes 66 and 69 of the vertebral body 26. As FIG. 12 shows, asingle offset structure 20 introduced by transpedicular access, forms acavity 38 that, while still laterally offset to one side of the middleregion MR (as shown in FIG. 8), is nevertheless symmetric in atop-to-bottom respect with the middle region MR. A matching, adjacentcavity can be formed by transpedicular deployment of a second offsetstructure 20 on the opposite lateral side of the vertebral body 26. Thecomposite cavity, formed by the two offset bodies 20, introducedsimultaneously or in succession by dual transpedicular access, issubstantially centered in all respects about the middle region MR.

FIG. 13 shows the offset expandable structure 20 deployed by apostero-lateral approach in the interior volume 30 of a vertebral body26. As before shown in FIG. 9, the postero-lateral approach in FIG. 13does not align the catheter tube axis 24 with the natural axes 66 and 67of the body 26. The expansion of the offset structure 20, which isasymmetric about the catheter tube axis 24, is nevertheless generallysymmetric with respect to all natural axes 66, 67, and 69 of thevertebral body 26. A single offset structure 20, deployed bypostero-lateral access, forms a cavity 38′, which is substantiallycentered about the middle region MR.

A cavity centered with respect to the middle region MR provides supportuniformly across the middle region MR when filled with bone cement. Thecapability of the vertebral body 26 to withstand loads is therebyenhanced. The symmetric compaction of cancellous bone 32 in the interiorvolume 30 that a centered cavity provides also exerts more equal anduniform interior forces upon cortical bone 32, to elevate or push brokenand compressed bone.

FIGS. 14A and 14B show an expandable structure 200 having an offset,asymmetric geometry different than the geometry of the offset expandablestructure 20 shown in FIGS. 11A and 115. In FIGS. 11A and 115, theoffset angle A between the cylinder axis 22 and the catheter tube axis24 is an acute angle. As a result, the axis 22 of the structure 20 isoffset in a nonparallel dimension or plane relative to the catheter tubeaxis 24. In FIGS. 14A and 14B, the offset angle A between the cylinderaxis 220 and the catheter tube axis 240 is zero, as the axis 220 of thecylinder 210 is offset at a distance from and in a generally paralleldimension or plane relative to the catheter tube axis 240. The cathetertube 160 can, at its proximal end, be configured like the tube 50 shownin FIG. 3, with a handle 51 made of, e.g., a foam material.

As in FIGS. 11A and 11B, the tops 250 of conical portions 340 aresecured about the catheter tube 160 and, in this respect, are generallyaligned with the catheter tube axis 240. In FIGS. 14A and 14B, theorientation of the bases 270 of the conical portions 340 differ. In FIG.14A, the bases 270 of the conical portions 340 extend generallyperpendicularly to the catheter tube axis 240, and are thereforegenerally parallel to the tops 250 (comparable to the orientation shownin FIG. 11B). In FIG. 143, the bases 270 of the conical portions 340extend at an angle B to the catheter tube axis 240. In this orientation,the tops 250 and the bases 270 are not parallel to each other.

FIGS. 11A and 11B and 14A and 14B show that it is possible, byadjustment of the offset angle A, as well as adjustment of theorientation of the conical end bases, to achieve virtually any desiredoffset geometry, and thereby tailor the orientation of the expandablestructure to the particular geometry of the point of use.

B. Maximizing Cancellous Bone Compaction

Referring back to FIG. 4, when the conventional tubular structure 56shown in FIG. 4 is substantially expanded, material of the structure isstretched into conical sections 62 near the ends 58, which are bonded tothe catheter tube 50. FIG. 15 shows the geometry of expanded tubularstructure 56 in greater detail. The conical portions 62 extend at a coneangle α from the bonded ends 58. The expanded structure 56 thereforepresents the generally cylindrical middle region 64, where the maximumdiameter of the structure 56 (BODY_(DIA)) exists, and the conicalportions 62, which comprise regions of diameter that decreases withdistance from the middle region 64 until reaching the diameter of thecatheter tube (TUBE_(DIA)).

Due to the geometry shown in FIG. 15, maximum cancellous bone compactiondoes not occur along the entire length (L2) of the conventionalstructure 56, as measured between the bonded ends 58. Instead, maximumcancellous bone compaction occurs only along the effective length (Ll)of the cylindrical middle region 64 of the structure 56, where thestructure 56 presents its maximum diameter BODY_(DIA). Cancellous bonecompaction diminishes along the length of the conical portions 62, wherethe structure's diameter progressively diminishes. At the bonded ends58, and portions of the catheter tube 50 extending beyond the bondedends 58, no bone compaction occurs. The catheter tube 50 can, at itsproximal end, be configured like the tube 50 shown in FIG. 3, with ahandle 51 made of, e.g., a foam material.

The lengths (Lc) of the conical regions 62 and bonded ends 58 relativeto the entire length of the structure 56 (L2) are important indicationsof the overall effectiveness of the structure 56 for compactingcancellous bone. The effective bone compaction length (Ll) of anyexpandable structure having conical end regions, such as structure 56shown in FIG. 15, can be expressed as follows:

Ll=L2−2(Lc)

where the length of a given conical region (Lc) can be expressed asfollows:

${Lc} = \frac{h}{\tan \frac{\alpha}{2}}$

where:

$h = \frac{{BODY}_{DIA} - {TUBE}_{DIA}}{2}$

where (see FIG. 15):

-   -   BODY_(DIA) is the maximum diameter of the middle region 64, when        substantially expanded,    -   TUBE_(DIA) is the diameter of the catheter tube 50, and    -   α is the angle of the conical portion.

As the foregoing expressions demonstrate, for a given conical angle α,the length Lc of the conical portions 62 will increase with increasingmaximum diameter BODY_(DIA) of the middle region 64. Thus, as BODY_(DIA)is increased, to maximize the diameter of the formed cavity, the lengthsLc of the conical portions 62 also increase, thereby reducing theeffective length L1 of maximum cancellous bone compaction.

The bone compaction effectiveness of an expandable structure of a givenmaximum diameter increases as L1 and L2 become more equal. The geometryof a conventional tubular structure 56 shown in FIG. 15 poses a tradeoffbetween maximum compaction diameter and effective compaction length.This inherent tradeoff makes optimization of the structure 56 for bonecompaction application difficult.

FIG. 16 shows an improved structure 70 having a geometry, whensubstantially expanded, which mitigates the tradeoff between maximumcompaction diameter and effective compaction length. The structure 70includes a middle region 72, where BODY_(DIA) occurs. The structure 70also includes end regions 74, which extend from the middle region 72 tothe regions 76, where the material of the structure is bonded to thecatheter tube 78, at TUBE_(DIA). The catheter tube 78 can, at itsproximal end, be configured like the tube 50 shown in FIG. 3, with ahandle 51 made of, e.g., a foam material.

In the embodiment shown in FIG. 16, the end regions are molded orstressed to provide a non-conical diameter transformation betweenBODY_(DIA) and TUBE_(DIA). The diameter changes over two predefinedradial sections r1 and r2, forming a compound curve in the end regions74, instead of a cone. The non-conical diameter transformation of radialsections r1 and r2 between BODY_(DIA) and TUBE_(DIA) reduces thedifferential between the effective bone compaction length L1 of thestructure 70 and the overall length L2 of the structure 70, measuredbetween the bond regions 76.

FIG. 17 shows another improved expandable structure 80 having a geometrymitigating the tradeoff between maximum compaction diameter andeffective compaction length. Like the structure 70 shown in FIG. 16, thestructure 80 in FIG. 16 includes a middle region 82 of BODY_(DIA), andend regions 84 extending from the middle region to the bonded regions86, at TUBE_(DIA). As the structure 70 in FIG. 16, the end regions 84 ofthe structure 80 make a non-conical diameter transformation betweenBODY_(DIA) and TUBE_(DIA). In FIG. 17, the predefined radial sections r1 and r 2 are each reduced, compared to the radial section r1 and r2 inFIG. 16. As a result, the end regions 84 take on an inverted profile. Asa result, the entire length L2 between the bonded regions 86 becomesactually less than the effective length L1 of maximum diameterBODY_(DIA). The catheter tube can, at its proximal end, be configuredlike the tube 50 shown in FIG. 3, with a handle 51 made of, e.g., a foammaterial.

The structures 70 and 80, shown in FIGS. 16 and 17, when substantiallyinflated, present, for a given overall length L2, regions ofincreasingly greater proportional length L1, where maximum cancellousbone compaction occurs.

Furthermore, as in FIG. 17, the end regions 84 are inverted about thebonded regions 86. Due to this inversion, bone compaction occurs incancellous bone surrounding the bonded regions 86. Inversion of the endregions 84 about the bonded regions 86 therefore makes it possible tocompact cancellous bone along the entire length of the expandablestructure 80.

FIG. 18 shows another embodiment of an improved expandable structure 90.Like the structure 80 shown in FIG. 17, the structure 90 includes amiddle region 92 and fully inverted end regions 94 overlying the bondregions 96. The structure 80 comprises, when substantially collapsed, asimple tube. At least the distal end of the tubular structure 80 ismechanically tucked or folded inward and placed into contact with thecatheter tube 98. As shown in FIG. 18, both proximal and distal ends ofthe tubular structure are folded over and placed into contact with thecatheter tube 98. The catheter tube 98 can, at its proximal end, beconfigured like the tube 50 shown in FIG. 3, with a handle 51 made of,e.g., a foam material.

The catheter tube 98 is dipped or sprayed beforehand with a material 102that absorbs the selected welding energy, for example, laser energy. Thefolded-over ends 94 are brought into abutment against the material 102.The welding energy transmitted from an external source through themiddle region 92 is absorbed by the material 102. A weld forms, joiningthe material 102, the folded-over ends 94, and the catheter tube 50. Theweld constitutes the bond regions 96.

The inverted end regions 94 of the structure 90 achieve an abrupttermination of the structure 90 adjacent the distal end 104 of thecatheter tube 98, such that the end regions 94 and the distal cathetertube end 104 are coterminous. The structure 90 possesses a region ofmaximum structure diameter, for maximum cancellous bone compaction,essentially along its entire length. The structure 90 presents noportion along its length where bone compaction is substantially lessenedor no cancellous bone compaction occurs.

FIGS. 19 and 20 show another embodiment of an expandable structure 110.As FIG. 20 shows, the structure 110 includes a middle region 112 ofmaximum diameter BODY_(DIA) and inverted end regions 114, which overliethe bonded regions 116.

FIG. 19 shows the structure 110 before the end regions 114 have beeninverted in the manufacturing process. As FIG. 19 shows, the structure110 comprises, when substantially collapsed, a simple tube. Tofacilitate formation of the inverted end regions 114 and bonded regions116, a two-piece catheter tube is provided, comprising an outer cathetertube 118 and an inner catheter tube 120. The inner catheter tube 120slides within the outer catheter tube 118. The catheter tube 118 can, atits proximal end, be configured like the tube 50 shown in FIG. 3, with ahandle 51 made of, e.g., a foam material.

As FIG. 19 shows, during the manufacturing process, the inner cathetertube 120 is moved a first distance d1 beyond the outer catheter tube118. In this condition, the proximal and distal ends 122 and 124 of thetubular structure 110 are bonded, without folding over or tucking in,about the inner catheter tube 118 and the outer catheter tube 120,respectively. The unfolded ends 122 and 124 of the tubular structure 110can then be directly exposed to conventional adhesive or melt bondingprocesses, to form the bonded regions 116.

Once the bonded regions 116 are formed, the inner catheter tube 120 ismoved (see arrow 130 in FIG. 20) to a distance d2 (shorter than d1) fromthe end of the outer catheter tube 118. The shortening of the inner tube120 relative to the outer tube 120 inverts the ends 122 and 124. Theinversion creates double jointed end regions 116 shown in FIG. 20, whichoverlie the bonded regions 116. The relative position of the outer andinner catheter tubes 118 and 120 shown in FIG. 20 is secured againstfurther movement, e.g., by adhesive, completing the assemblage of thestructure 110.

The double jointed inverted ends 114 of the structure 110 in FIG. 20,like single jointed inverted ends 94 of the structure 90 in FIG. 18,assure that no portion of the catheter tube protrudes beyond theexpandable structure. Thus, there is no region along either structure 94or 114 where cancellous bone compaction does not occur. Like thestructure 90 shown in FIG. 18, the structure 110 in FIG. 20 presents amaximum diameter for maximum cancellous bone compaction essentiallyalong its entire length.

FIG. 21 shows another embodiment of an improved expandable structure 300well suited for deployment in an interior body region. Like thestructure 110 shown in FIGS. 19 and 20, the structure 300 in FIG. 21includes an inner catheter tube 304 secured within an outer cathetertube 302. Like the structure 110 shown in FIGS. 19 and 20, the distalend 310 of the inner catheter tube 304 in FIG. 21 extends beyond thedistal end 308 of the outer catheter tube 302.

The outer diameter of the inner catheter tube 304 is likewise smallerthan the inner diameter of the outer catheter tube 302. A flow passage312 is defined by the space between the two catheter tubes 302 and 304.

The proximal end 314 of an expandable body 306 is bonded to the distalend 308 of the outer catheter tube 302. The distal end 316 of theexpandable body 306 is bonded to the distal end 310 of the innercatheter tube 304. An inflation medium 318 is conveyed into the body 306through the flow passage 312, causing expansion of the body 306.

In FIG. 21, the physical properties of the structure 300 at the proximalbody end 314 differ from the physical properties of the structure 300 atthe distal body end 316. The different physical properties are createdby material selection. More particularly, materials selected for theinner catheter tube 304 and the expandable body 306 are more compliant(i.e., more elastic) than the materials selected for the outer cathetertube 302. In a preferred embodiment, materials selected for theexpandable body 306 and the inner catheter tube 304 possess hardnessproperties of less than about 90 Shore A and ultimate elongation ofgreater than about 450%, e.g., more compliant polyurethanes. In apreferred embodiment, materials selected for the outer catheter tube 302possess hardness properties of greater than about 45 Shore D andultimate elongation of less than about 450%, e.g., less compliantpolyurethanes or polyethylenes.

Due to the differential selection of materials, the lack of complianceof the outer catheter tube 302 at the proximal body end 314 iscounterpoised during expansion of the body 306 against the compliance ofthe inner catheter tube 304 at the distal, body end 316. The differentcompliance characteristics causes the body 306, during expansion, toincrease in length in proportion to its increase in diameter duringexpansion. By virtue of the more compliant body 306 and inner cathetertube 304, the structure 300 shown in FIG. 21 is elastic enough toconform to an interior body region, like inside a bone. Nevertheless,the structure 300 is constrained from over-expansion by attachment ofthe proximal end 314 of the body 306 to the less elastic outer cathetertube 302.

The bond between a given expandable structure and its associatedcatheter tube can be strengthened by using a CO2 or NdYAG laser to weldthe structure and tube materials together. Factors influencing jointstrength include energy wave length, energy pulse width, pulse period,head voltage, spot size, rate of rotation, working distance, angle ofattack, and material selection.

The catheter tube 302 can, at its proximal end, be configured like thetube 50 shown in FIG. 3, with a handle 51 made of, e.g., a foammaterial.

II. Deployment in the Vasculature

FIG. 22 shows a blood vasculature region 400. The region 400 includes afirst blood vessel 402, which extends along a first axis 404. The region400 also includes a second blood vessel 406, which branches from thefirst blood vessel 402 along a second axis 408 offset from the firstaxis 404.

FIG. 22 also shows the presence of an occlusion 410 adjacent the secondblood vessel 406. The occlusion 410 can comprise, e.g., plaque buildupalong the interior wall of the second blood vessel 406.

FIG. 23 shows the distal end of a tool 412, which has been introducedinto the vascular region 400 for the purpose of opening the occlusion410. The tool 412 comprises a catheter tube 416, which carries at itsdistal end an expandable structure 420 of the type shown in FIG. 11. Thecatheter tube 416 can, at its proximal end, be configured like the tube50 shown in FIG. 3, with a handle 51 made of, e.g., a foam material.

The catheter tube 416 is introduced by conventional vascular introducerand, with fluoroscopic monitoring, steered to the targeted region 400along a guidewire 430 deployed within the first and second vessels 402and 406. The structure 420 is expanded using a sterile fluid, likesaline or a radio-contrast medium. FIG. 23 shows the structure 420 in asubstantially expanded condition.

Like the expandable structure 20 shown in FIG. 11, the main axis 422 ofthe structure 420 shown in FIG. 23 and the axis 424 of the catheter tube416 are not aligned. Instead, the structure axis 422 is offset at aselected acute angle A from the catheter tube axis 424. Due to theoffset angle A, the structure 420, when substantially expanded (as FIG.23 shows), is not symmetric with respect to the catheter tube axis 424.

As FIG. 23 shows, the asymmetric expansion of the structure 420 allowsthe physician to maintain the catheter tube 416 in axial alignment withthe first blood vessel 402, while maintaining the expandable structure420 in axial alignment with the second blood vessel 406. In thisorientation, expansion of the structure 420 within the second bloodvessel 406 opens the occlusion 410. The asymmetry of the structure 420relative to the catheter tube 416 thereby permits access to branchedblood vessels without complex manipulation and steering.

III. Deflection of the Structure

In all of the foregoing embodiments, a length of the associated cathetertube extends within the expandable structure. In the embodiments shownin FIGS. 4, 11A/B, 14A/B, and 15 to 18, the enclosed catheter tubecomprises an extension of the main catheter tube. In the embodimentsshown in FIGS. 19 to 21, the enclosed catheter tube comprises a separatecatheter tube carried by the main catheter tube.

Regardless of the particular construction (see FIG. 26), the enclosedlength of catheter tube 600 provides an interior lumen 602 passingwithin the expandable structure 604. The lumen 602 accommodates thepassage of a stiffening member or stylet 606 made, e.g., from stainlesssteel or molded plastic material.

The presence of the stylet 606 serves to keep the structure 604 in thedesired distally straightened condition during passage through anassociated guide sheath 608 toward the targeted body region 610, as FIG.26 shows. Access to the target body region 610 through the guide sheath608 can be accomplished using a closed, minimally invasive procedure orwith an open procedure.

As shown in FIG. 27, the stylet 606 can have a preformed memory, tonormally bend the distal region 612 of the stylet 606. The memory isovercome to straighten the stylet 606 when confined within the guidesheath 608, as FIG. 26 shows. However, as the structure 604 and stylet606 advance free of the guide sheath 608 and pass into the targetedregion 610, the preformed memory bends the distal stylet region 612. Thebend of the distal stylet region 612 bends the tube 600 and therebyshifts the axis 614 of the attached expandable structure 604 relative tothe axis 616 of the access path (i.e., the guide sheath 608). Thepresent stylet 606, positioned within the interior of the structure 604,further aids in altering the geometry of the structure 604 in accordancewith the orientation desired when the structure 604 is deployed for usein the targeted region 610.

IV. Material Selection

In any of the foregoing embodiments, the material of the expandablestructure can be selected according to the therapeutic objectivessurrounding its use. For example, materials including vinyl, nylon,polyethylenes, ionomer, polyurethane, and polyethylene tetraphthalate(PET) can be used. The thickness of the structure is typically in therange of 2/1000ths to 25/1000ths of an inch, or other thicknesses thatcan withstand pressures of up to, for example, 250-500 psi.

If desired, the material for the structure can be selected to exhibitgenerally elastic properties, like latex. Alternatively, the materialcan be selected to exhibit less elastic properties, like silicone. Usingexpandable bodies with generally elastic or generally semi-elasticproperties, the physician monitors the expansion to assure thatover-expansion and wall failure do not occur. Furthermore, expandablebodies with generally elastic or generally semi-elastic properties mayrequire some form of external or internal restraints to assure properdeployment in bone. The use of internal or external restraints inassociation with expandable bodies used to treat bone is discussed ingreater detail in copending U.S. patent application Ser. No. 08/485,394,filed Jun. 7, 1995, which is incorporated herein by reference.

Generally speaking, for use in treating bone, providing relativelyinelastic properties for the expandable structure, while not alwaysrequired, is nevertheless preferred, when maintaining a desired shapeand size within the bone is important, for example, in a vertebral body,where the spinal cord is nearby. Using relatively inelastic bodies, theshape and size can be better predefined, taking into account the normaldimensions of the outside edge of the cancellous bone. Use of relativelyinelastic materials also more readily permits the application ofpressures equally in a defined geometry to compress cancellous bone.

When treating bone, the choice of the shape and size of an expandablestructure takes into account the morphology and geometry of the site tobe treated. The shape of the cancellous bone to be compressed, and thelocal structures that could be harmed if bone were movedinappropriately, are generally understood by medical professionals usingtextbooks of human skeletal anatomy along with their knowledge of thesite and its disease or injury. The physician is also able to select thematerials and geometry desired for the structure based upon prioranalysis of the morphology of the targeted bone using, for example,plain films, spinous process percussion, or MRI or CRT scanning. Thematerials and geometry of the structure are selected to optimize theformation of a cavity that, when filled with bone cement, providesupport across the middle region of the bone being treated.

In some instances, it is desirable, when creating a cavity, to also moveor displace the cortical bone to achieve the desired therapeutic result.Such movement is not per se harmful, as that term is used in thisSpecification, because it is indicated to achieve the desiredtherapeutic result. By definition, harm results when expansion of thestructure results in a worsening of the overall condition of the boneand surrounding anatomic structures, for example, by injury tosurrounding tissue or causing a permanent adverse change in bonebiomechanics.

As one general guideline, the selection of the geometry of theexpandable structure should take into account that at least 40% of thecancellous bone volume needs to be compacted in cases where the bonedisease causing fracture (or the risk of fracture) is the loss ofcancellous bone mass (as in osteoporosis). The preferred range is about30% to 90% of the cancellous bone volume. Compacting less of thecancellous bone volume can leave too much of the diseased cancellousbone at the treated site. The diseased cancellous bone remains weak andcan later collapse, causing fracture, despite treatment.

Another general guideline for the selection of the geometry of theexpandable structure is the amount that the targeted fractured boneregion has been displaced or depressed. The expansion of the structurewithin the cancellous bone region inside a bone can elevate or push thefractured cortical wall back to or near its anatomic position occupiedbefore fracture occurred.

However, there are times when a lesser amount of cancellous bonecompaction is indicated. For example, when the bone disease beingtreated is localized, such as in avascular necrosis, or where local lossof blood supply is killing bone in a limited area, the expandablestructure can compact a smaller volume of total bone. This is becausethe diseased area requiring treatment is smaller.

Another exception lies in the use of an expandable structure to improveinsertion of solid materials in defined shapes, like hydroxyapatite andcomponents in total joint replacement. In these cases, the structureshape and size is defined by the shape and size of the material beinginserted.

Yet another exception lays the use of expandable bodies in bones tocreate cavities to aid in the delivery of therapeutic substances, asdisclosed in copending U.S. patent application Ser. No. 08/485,394,previously mentioned. In this case, the cancellous bone may or may notbe diseased or adversely affected. Healthy cancellous bone can besacrificed by significant compaction to improve the delivery of a drugor growth factor which has an important therapeutic purpose. In thisapplication, the size of the expandable structure is chosen by thedesired amount of therapeutic substance sought to be delivered. In thiscase, the bone with the drug inside is supported while the drug works,and the bone heals through exterior casting or current interior orexterior fixation devices.

The materials for the catheter tube are selected to facilitateadvancement of the expandable structure into cancellous bone. Thecatheter tube can be constructed, for example, using standard flexible,medical grade plastic materials, like vinyl, nylon, polyethylenes,ionomer, polyurethane, and polyethylene tetraphthalate (PET). Thecatheter tube can also include more rigid materials to impart greaterstiffness and thereby aid in its manipulation. More rigid materials thatcan be used for this purpose include stainless steel, nickel-titaniumalloys (Nitinol™ material), and other metal alloys.

V. Single Use

Expansion of any one of the expandable structures described hereinduring first use in a targeted body region generates stress on thematerial or materials which make up the structure. The material stresscreated by operational loads during first use in a targeted body regioncan significantly alter the molded morphology of the structure, makingfuture performance of the structure unpredictable.

For example, expansion within bone during a single use creates contactwith surrounding cortical and cancellous bone. This contact can damagethe structure, creating localized regions of weakness, which may escapedetection. The existence of localized regions of weakness canunpredictably cause overall structural failure during a subsequent use.

In addition, exposure to blood and tissue during a single use can entrapbiological components on or within the structure or the associatedcatheter tube. Despite cleaning and subsequent sterilization, thepresence of entrapped biological components can lead to unacceptablepyrogenic reactions.

As a result, following first use, the structure can not be relied uponto reach its desired configuration during subsequent use and may nototherwise meet established performance and sterilization specifications.The effects of material stress and damage caused during a single use,coupled with the possibility of pyrogen reactions even afterresterilization, reasonably justify imposing a single use restrictionupon devices which carry these expandable structures for deployment inbone.

To protect patients from the potential adverse consequences occasionedby multiple use, which include disease transmission, or material stressand instability, or decreased or unpredictable performance, theinvention also provides a kit 500 (see FIGS. 24 and 25) for storing asingle use probe 502, which carries an expandable structure 504described herein prior to deployment in bone.

In the illustrated embodiment (see FIGS. 24 and 25), the kit 500includes an interior tray 508. The tray 508 holds the probe 502 in alay-flat, straightened condition during sterilization and storage priorto its first use. The tray 508 can be formed from die cut cardboard orthermoformed plastic material. The tray 508 includes one or more spacedapart tabs 510, which hold the catheter tube 503 and expandablestructure 504 in the desired lay-flat, straightened condition. As shown,the facing ends of the tabs 510 present a nesting, serpentine geometry,which engages the catheter tube 503 essentially across its entire width,to securely retain the catheter tube 503 on the tray 608.

The kit 500 includes an inner wrap 512, which is peripherally sealed byheat or the like, to enclose the tray 508 from contact with the outsideenvironment. One end of the inner wrap 512 includes a conventionalpeal-away seal 514 (see FIG. 25), to provide quick access to the tray508 upon instance of use, which preferably occurs in a sterileenvironment, such as within an operating room.

The kit 500 also includes an outer wrap 516, which is also peripherallysealed by heat or the like, to enclosed the inner wrap 512. One end ofthe outer wrap 516 includes a conventional peal-away seal 518 (see FIG.25), to provide access to the inner wrap 512, which can be removed fromthe outer wrap 516 in anticipation of imminent use of the probe 502,without compromising sterility of the probe 502 itself.

Both inner and outer wraps 512 and 516 (see FIG. 25) each includes aperipherally sealed top sheet 520 and bottom sheet 522. In theillustrated embodiment, the top sheet 520 is made of transparent plasticfilm, like polyethylene or MYLAR™ material, to allow visualidentification of the contents of the kit 500. The bottom sheet 522 ismade from a material that is permeable to EtO sterilization gas, e.g.,TYVEC™ plastic material (available from DuPont).

The sterile kit 500 also carries a label or insert 506, which includesthe statement “For Single Patient Use Only” (or comparable language) toaffirmatively caution against reuse of the contents of the kit 500. Thelabel 506 also preferably affirmatively instructs againstresterilization of the probe 502. The label 506 also preferablyinstructs the physician or user to dispose of the probe 502 and theentire contents of the kit 500 upon use in accordance with applicablebiological waste procedures. The presence of the probe 502 packaged inthe kit 500 verifies to the physician or user that probe 502 is sterileand has not be subjected to prior use. The physician or user is therebyassured that the expandable structure 504 meets established performanceand sterility specifications, and will have the desired configurationwhen expanded for use.

The features of the invention are set forth in the following claims.

1-14. (canceled)
 15. An instrument comprising: a catheter tube having aproximal end, a distal end, a first portion defining a first lumen, asecond portion defining a second lumen, the first and second lumensbeing coaxial and having a circular cross-section; and an expandablestructure being disposed at the distal end of the catheter tube andhaving a proximal end, a distal end, and an outer surface and, theproximal end of the expandable structure is secured to the first portionand the distal end of the expandable structure is secured to the secondportion, wherein the second portion extends through the first lumen ofthe catheter tube to the distal end of the expandable structure.
 16. Aninstrument as recited in claim 15, further comprising a stylet disposedwith the second lumen.
 17. An instrument as recited in claim 16, whereinthe stylet is removable from the second lumen.
 18. An instrument asrecited in claim 16, wherein the stylet is slidably disposed within thesecond lumen.
 19. An instrument as recited in claim 15, wherein a spacebetween the first and second lumens defines an unobstructed flow passageconfigured for delivery of a fill material into the expandablestructure.
 20. An instrument as recited in claim 15, wherein no part ofthe catheter tube protrudes beyond the expandable structure when theexpandable structure is in an expanded state.
 21. An instrumentcomprising: an outer catheter tube including a distal end and a firstlumen having a substantially circular cross-sectional configuration; aninner catheter tube extending within the outer catheter tube andincluding a distal end and a second lumen having a circularcross-sectional configuration, the first and second lumens being coaxialand the distal end of the inner catheter tube extending beyond thedistal end of the outer catheter tube; and an expandable structurecommunicating with the first lumen, the expandable structure having anouter surface, a proximal end secured to the first lumen, a distal endsecured to a distal end of the second lumen wherein no portion of theouter catheter tube protrudes beyond the expandable structure such thatthe entire outer surface of the expandable structure is continuous. 22.An instrument as recited in claim 21, wherein the expandable structureincludes a proximal end and distal end and wherein the distal end of theexpandable structure is attached to the distal end of the inner cathetertube.
 23. An instrument as recited in claim 21, further comprising astylet disposed in the second lumen.
 24. An instrument as recited inclaim 23, wherein the stylet includes a region with a preformed memory.25. An instrument as recited in claim 23, wherein the stylet includes aregion having a bent configuration.
 26. An instrument as recited inclaim 23, wherein the stylet includes a region having a bentconfiguration, the elongated member comprising a preformed memory suchthat the region returns to the bent configuration if straightened. 27.An instrument as recited in claim 21, further comprising a guide sheathsized for through passage of the stylet and catheter tubes.
 28. Aninstrument as recited in claim 21, wherein the inner catheter tube isformed from a material more compliant than the material from which theouter catheter tube is formed.
 29. An instrument as recited in claim 21,wherein a space between the inner and outer catheter tubes defines anunobstructed flow passage configured for delivery of a fill materialinto the expandable structure.
 30. A method for creating a cavity in aninterior body region of a patient, comprising: providing an instrumentcomprising: a catheter tube having a proximal end, a distal end, a firstportion defining a first lumen, a second portion defining a secondlumen, the first and second lumens being coaxial and having a circularcross-section, and an expandable structure being disposed at the distalend of the catheter tube and having a proximal end, a distal end, and anouter surface and, the proximal end of the expandable structure issecured to the first portion, the distal end of the expandable structureis secured to the second portion and the second portion extends throughthe first lumen of the catheter tube to the distal end of the expandablestructure; positioning the expandable structure within the interior bodyregion with the expandable structure in a collapsed configuration; andmoving the expandable structure from the collapsed configuration to anexpanded configuration to create the cavity.
 31. A method as recited inclaim 30, further comprising: positioning a guide wire in the interiorbody region; and steering the instrument along the guide wire to atargeted region within the interior body region.
 32. A method as recitedin claim 30, wherein moving the expandable structure from the collapsedconfiguration to the expanded configuration comprises delivering aninflation material through an unobstructed flow passage defined by aspace between the first and second lumens and into an interior chamberof the expandable structure.
 33. A method as recited in claim 30,wherein the expandable structure has a first portion adjacent theproximal end of the expandable structure, a second portion adjacent thedistal end of the expandable structure and a third portion between thefirst and second portions, the first and second portions each having aconical configuration and the third portion having a cylindricalconfiguration.
 34. A method as recited in claim 30, wherein no part ofthe catheter tube protrudes beyond the expandable structure when theexpandable structure is in the expanded configuration.